Synthesis and Characterization of Stable Isotope Labeled 3,3',4,4'-Tetrachlorobiphenyl-D6

A new synthetic method of the stable isotope labeled 3,3',4,4'-tetrachlorobiphenyl-D6 was investigated. The synthesis of 3,3',4,4'-tetrachlorobiphenyl-D6 is based on 1,2-dichlorobenzene-D4 as the labeling precursor through three steps of catalyzed borylation，iodination，Suzuki coupling reaction. According to the amount of 1,2-dichlorobenzene-D4，the yield of 3,3',4,4'-tetrachlorobiphenyl-D6 was 72.85%. The structure of the target product was characterized by 1H-NMR，gas-mass spectrometry and gas chromatography. The chemical purity of 3,3',4,4'-tetrachlorobiphenyl-D6 was 99.54%，and the abundance of deuterium isotope was 98.38 atom%D. It can be used as the isotope internal standard for the determination of polychlorinated biphenyls.